This invention relates to the field of firearms, and in particular to the U.S. Army's standard M-16 series rifle, including but not limited to the M16, M16A1, M16A2, M16A2E1, XM4 Carbine, M231 Firing Port weapon, XM177 Submachinegun, and commercial variations thereof.
The conventional M16 Rifle is designed so the spent cartridge case strikes a small deflector rib at the back of what is known as the ejection port and rebounds forward at about 45.degree.. At the rifle's cyclic rate of fire decreases, the ejection pattern slowly shifts rearward. At around 725 rounds per minute, the spent case misses the current deflector rib and spins back almost parallel to the side of the rifle, on the right side looking from the shooter's perspective. For left handed riflemen, this condition is dangerous because the hot spent cases strike them in the face and neck, sometimes causing burns. In one unfortunate incident for a left handed shooter, a burning hot case rolled inside his open shirt neck, eventually burning his stomach areas; panic shooting led to accidental death of one soldier and wounding of still others. For the right handed soldier, such spent cases would probably just go over the right shoulder where the rifle butt rests, if they missed the back end of the ejection port. For a left-hander, however, the rifle butt rests on the left shoulder; the fired cases which miss the rib would then likely hit him in the face or neck. Yet some 18-22% of soldiers statistically are estimated to be left-handed. Clearly then, any improvement to safeguard the left handed shooter against spent cases is greatly needed, especially with the M-16, given its widespread use by the Marines and Army as a standard weapon.